This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Understanding the link between HIV, methamphetamine abuse and changes in the serotonin system is critical to designing new preventative and therapeutic strategies for both AIDS and methamphetamine addiction, which have high co-morbidity. This project investigates the epigenetic regulation of serotonin neurotransmission and its relevance to HIV and methamphetamine abuse. We anticipate that the research findings generated from this project will provide new insights into the regulation of the serotonin system and will lead to new strategies to treat HIV-infection and methamphetamine addiction and their co-morbidity.